Electronhole asymmetric integer and fractional quantum Hall effect in bilayer graphene
Abstract
The nature of fractional quantum Hall (FQH) states is determined by the interplay between the Coulomb interaction and the symmetries of the system. The distinct combination of spin, valley, and orbital degeneracies in bilayer graphene is predicted to produce an unusual and tunable sequence of FQH states. Here, we present local electronic compressibility measurements of the FQH effect in the lowest Landau level of bilayer graphene. We observe incompressible FQH states at filling factors ν = 2p + 2/3, with hints of additional states appearing at ν = 2p + 3/5, where p = 2, 1, 0, and 1. This sequence breaks particlehole symmetry and obeys a ν → ν + 2 symmetry, which highlights the importance of the orbital degeneracy for manybody states in bilayer graphene.
 Publication:

Science
 Pub Date:
 July 2014
 DOI:
 10.1126/science.1250270
 arXiv:
 arXiv:1312.7033
 Bibcode:
 2014Sci...345...55K
 Keywords:

 PHYSICS, AppliedPhysics, Physics, Engineering;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 Science 345, 6192 (2014)